It can be shown that moderate levels of ultrasonic sound waves propagating through tissue cause an oscillating fluctuation in tissue resistivity on the order of .03%/W/cm(2), at the same frequency as the sound. This ultrasound-tissue impedance interaction is consistent with the known effects of pressure waves on electrolytes. Experiments show that an observed interaction process between sound and currents applied to tissue may serve as the basis for a new approach to imaging internal body structure and perhaps function. In the proposed work, we plan to investigate the limits of the sensitivity of the technique and to gain insight into some of the variables of sound frequency, carrier current frequencies, and signal to noise ratios achievable by the use of in vitro tissue simulations.